#============================================================================#
# Specify the Hostname or the IP, the port and the protocol (tcp or udp) #
# to reach the OpenVPN Server. #
# The Hostname can be a dynamic FQDN such as a DynDNS one. #
#============================================================================#

remote XXXX XXXX

proto udp

#============================================================================#
# You must specify this parameter if you want the Username and Password #
# request to appear. Comment it if you only use X.509 Authentication. #
#============================================================================#

auth-user-pass

#============================================================================#
# You need to specify the file which contains the certificate (PEM format) #
# of the Certification Authority that signed the OpenVPN server certificate. #
# You can export it by clicking the hyperlink CA on the login page of #
# ZeroShell. #
# Notice that you need to specify this parameter also if you use #
# “Password Only” Authentication. #
#============================================================================#

BEGIN CERTIFICATE
END CERTIFICATE

#============================================================================#
# If you want to use the Client X.509 Authentication you must specify #
# a client certificate and the related private key in pem format. #
# You can merge both in the same file. #
#============================================================================#

#============================================================================#
# You should not need to change these settings. #
#============================================================================#

Hi,
I use linux client (linux mint ), and work flawless but, it was a huge pain to set it up.
There are a lot of parameters to match.
I use the simple password only. You should start with this, make it to work, and then go further.

Then on client I had to check LZO compression and TCP (because I use TCP port), default I think is UDP. This was the reason for me why I got the connection error.
Then Under the security client I picked the same cipher AES-128-CBC and hashing (HMAC Authentication) to SHA1
This was the reason for my authentication errors.. 😉

Make sure you check the instructions on the VPN board and other HowTos